Minimally invasive surgical procedures, such as percutaneous transluminal coronary angioplasty (PTCA), have become increasingly common. A PTCA procedure involves the insertion of a catheter into a coronary artery to position an angioplasty balloon at the site of a stenotic lesion that is at least partially blocking the coronary artery. The balloon is then inflated to compress the stenosis and to widen the lumen in order to allow an efficient flow of blood through the coronary artery.
Following PTCA and other stenotic treatment procedures, a significant number of patients experience restenosis or other vascular blockage problems. These problems are prone to arise at the site of the former stenosis.
In order to help avoid restenosis and other similar problems, a stent may be implanted into the vessel at the site of the former stenosis with a stent delivery catheter. A stent is a tubular structure which is delivered to the site of the former stenosis or lesion and expanded to compress against vessel walls thereat, again with a balloon. The structure of the stent promotes maintenance of an open vessel lumen. The stent can be implanted in conjunction with the angioplasty.
A stent can also be used to provide for local delivery of a drug. For example, radiotherapy and drug delivery treatments applied to the site of the former stenosis following angioplasty have been found to aid in the healing process and to reduce significantly the risk of restenosis and other similar problems. Local delivery of drugs is often preferred over systemic delivery of drugs, particularly where high systemic doses are necessary to achieve an effect at a particular site. High systemic doses of drugs can often create adverse effects. One proposed method of local delivery is to coat the surface of a stent with a drug.
A stent is typically coated with a primer layer and a drug layer. The primer layer is applied between the stent and the drug layer to improve adhesion of the drug layer to the stent. In some cases, the drug layer may be applied directly to the stent.
Spray coating is commonly used to apply a layer of coating to a stent. A spray coating system typically includes a spray nozzle and a pump that supplies a coating substance from a reservoir to the spray nozzle. The coating substance is ejected through the nozzle and applied to the surface of the stent.
Current spray coating systems, however, are inefficient and unreliable, and produce a high defective rate. Additionally, it is difficult to keep track of the types of drugs coated on stents with current systems. Losing track of stent coating types may have grave consequences. Furthermore, some current systems may expose the operators to health risks due to extended exposure to drugs.
Therefore, there is a need for coating systems and methods that are efficient and reliable and reduce the operators' exposure to health risks.